Northern Michigan University(MARQUETTE, Mich.) -- Michigan police are investigating the drowning of a college soccer player at her school’s swimming pool after a team workout.

Arianna Alioto, 18, of Columbia, Mo., was found dead in Northern Michigan University’s pool at 5:30 Friday afternoon, about 30 minutes after her soccer team finished working out in the Marquette, Mich., pool.

“A student who was working out in the area that overlooks the pool reported to the recreational desk staff that it appeared someone was in the pool,” Mike Bath, director of the NMU Public Safety and Police Services said in a press conference Monday. “The staff immediately entered the pool area to find a female in the water, unresponsive. 911 was contacted and the staff began to administer CPR.”

Alioto was transported to a local hospital, where she was pronounced dead. An autopsy was performed Monday morning, but results won’t be available for another two to four weeks. There was no obvious physical trauma to Alioto’s body when she was taken out of the pool, and authorities are looking into any medical condition she might have had.

The investigation is being conducted by the NMU police, who were interviewing players, teammates and other possible witnesses, including the student who saw Alioto in the pool.

There is still confusion over if or when her teammates noticed she was missing. Authorities don’t yet know if she left the pool area with them, or was left behind when their workout was over. She was wearing her swimsuit when she was found.

Investigators are trying to determine when the lifeguard, also a university student, who was present for the team workout, left the pool area. The lifeguard who was on duty was gone by the time Alioto was spotted.

Alioto was a freshman at Northern Michigan University, and played forward and mid-field for the soccer team. She redshirted this season following a knee injury.

A group of about 200 students gathered Saturday for a vigil in Alioto’s memory, organized by some of her teammates, The Mining Journal reports.

In a statement, her coach said the team was shocked by her sudden death.

“It’s hard to grasp that Arianna was with us one moment and gone the next. It just doesn’t seem real. Her death is devastating,” Matt Granstrand said. “We will be grieving for her loss for a long time.”

A funeral is planned for Saturday, Dec. 8. The Physical Education Instructional Facility, where the pool is located, was reopened Sunday.